Actually I solved the problem, but I'll answer your questions for completeness in case they shed light that I don't yet know I need.

> The first question is.. do you have an https certification installed?

I have no idea. I don't know anything about running an HTTP server, let alone certification (whatever that is).

> I'm not familiar with VisualSVN but usually there is a directory/local you access svn with rather than just the root server url and also you have to specify the repository, unless there is only 1.
>
> Something like http://MyServerName/svn/repository

This is exactly the answer. I had asked the VisualSVN people and they told me this as well, and it worked.

> Does the VisualSVN manual tell you the path that is sets up to the repositories?

It has a GUI interface that lets me point-and-click to set up repositories. In another panel it tells me the path (to the server, I guess, but didn't tell me I needed to specify the repository. It wasn't obvious I needed to do that).